The May 5 email I received from Colorado Democratic Sen. Michael Bennet’s campaign committee opened with: “Larry Sabato in Politico: COLORADO IS ONE OF ONLY SEVEN 2016 TOSS-UPS. Colorado will decide the 2016 election!”

Forget the fact Sabato’s piece was talking about the Electoral College and the presidential contest, not the Senate race in the Centennial State. The Bennet campaign wants you to know control of the Senate after 2016 rests on Colorado, and you'd better dig deep into your pockets if you want to re-elect Bennet and assure a Democratic sweep in the state.

In fact, Sabato, the Cook Political Report and the Rothenberg & Gonzales Political Report/Roll Call all agree the Colorado Senate race, still in its infancy, leans toward the Democrat. It is not a tossup, no matter how many fundraising emails the Bennet campaign sends out.

Of course, this doesn’t mean it will never become a tossup. Contests develop, and vulnerabilities change. Republican strategists have not given up hope of recruiting a top-tier challenger, such as Rep. Mike Coffman, who might be able to mount the sort of come-from-behind effort then-Rep. Cory Gardner did to upset Democratic Sen. Mark Udall last cycle.

But even knowledgeable Republicans wouldn’t tell you the Colorado Senate race is close to a tossup now. And in their most candid moments they might even tell you the race may never get any closer than where it is now — leaning in Bennet's favor.

Bennet was first appointed to the Senate in 2009 to fill an open Democratic seat, and he won a competitive primary in 2010 and a very tough general election that same year.

He would have lost the general election race, in all likelihood, had Colorado Republicans not snatched defeat from the jaws of victory by nominating Ken Buck, rather than former Lt. Gov. Jane Norton, the favorite of the GOP establishment. (Buck, of course, made his way to Congress in last fall's election.)

Colorado is a competitive state, so it is no wonder observers are keeping an eye on its Senate contest in 2016. And given the paucity of GOP takeover opportunities next year, it isn’t surprising Republican strategists are hoping to keep alive the perception the Senate race is in play for as long as they can.

Bennet’s narrow win in 2010 and Udall’s narrow loss by 2.5 points last cycle are totally understandable and easily explained, and the explanations don’t automatically lead to the conclusion 2016 will be tight.

Democrats were divided in 2010 after a bitter Senate primary, and a strong national GOP partisan wave worked against the Democrat. No wonder Bennet found himself in a very difficult contest, winning by fewer than 30,000 votes.

Four years later, an even stronger Republican wave helped propel Gardner past Udall. Gardner was one of the most appealing candidates Republicans had put forward in a competitive or blue-leaning state in years, and only the combination of his personal appeal, the Udall campaign’s near-obsession with women’s issues and the national political dynamic allowed him to ride a partisan wave to victory.

Bennet’s uncomfortably narrow victory in 2010 and Udall’s loss in 2014 each occurred in an anti-Barack Obama, midterm election. That meant Republicans had the opportunity to turn each Senate election into a referendum on the president, who was not on the ballot.

Colorado voters who wanted to send a message of dissatisfaction about the president could only do so by voting against Bennet, and subsequently Udall. That is a different dynamic from the one that occurs in presidential election years, such as 2016.

Next fall, voters won’t automatically see the Senate race as a way to make a statement about the presidential race, and the GOP won’t have a strong voter turnout advantage, the way the party did in 2010 and 2014.

Republicans don’t have a candidate yet, and nobody knows whether they will end up with a strong recruit or a weak one.

Coffman, who is often mentioned as a potentially strong challenger to Bennet, has some assets — he’s a four-term House member who has won tough races before — and some liabilities — he’s a four-term House member with a long voting record.

In 2012, he made an unforced blunder at a fundraiser when he said, “I don’t know whether Barack Obama was born in the United States or not. But I do know this, that in his heart he’s not an American.” He won re-election that year and was re-elected again two years later, but Democrats undoubtedly would use that sound bite to introduce him to voters statewide.

Finally, history isn’t on the GOP’s side. According to CQ Roll Call data, incumbent senators from the same state and the same party have lost re-election in consecutive elections only once in the past 40 years. Iowa Democrat Dick Clark lost re-election in 1978, and Democrat John Culver lost re-election two years later, in 1980.

Democrats have plenty of reasons to keep Colorado on their radar screens, and Republicans have plenty of reasons to look for a strong challenger who can take advantage of the state’s fundamental competitiveness.

But right now, it is much easier for Democrats to defend the seat than it is for Republicans to win it back from Bennet.